Question 1

Sarah found a plant in the garden and measured its height. After two weeks, she measured its height again. From her observation, Sarah concluded that the plant is a living thing because it can____

Accepted Answer

(1) grow. Living things exhibit growth. The observation that the plant's height increased after two weeks is a direct demonstration of growth, a key characteristic of living organisms.

Question 2

Study the diagram below. What could Q be?

Accepted Answer

(2) reptile. The flowchart indicates that Q cannot make its own food (it's not a plant) and it has scales. Among the given options, only a reptile fits both criteria (heterotrophic and possessing scales).

Question 3

John made the following observations on the life cycle of an animal. • There are three stages in the life cycle. . The young looks like the adult. Which animal was John observing?

Accepted Answer

(4) cockroach. A cockroach undergoes incomplete metamorphosis with three stages: egg, nymph, and adult. The nymph (young) resembles a smaller version of the adult. Frogs, beetles, and butterflies either have more than three stages or the young do not resemble the adult.

Question 4

Which one of the following shows the correct order when food moves through some parts of the digestive system?

Accepted Answer

(3) stomach -> small intestine -> large intestine. Food first enters the stomach for initial digestion, then moves to the small intestine for most nutrient absorption, and finally to the large intestine for water absorption and waste formation.

Question 5

An object A was attracted to a magnet, as shown in the figure below. Object A is made of____

Accepted Answer

(1) iron. Magnets attract ferromagnetic materials. Among the given options, iron is a magnetic material that would be attracted to a magnet. Plastic, rubber, and wood are non-magnetic.

Question 6

Which one of the following properties is true for both air and a pencil?

Accepted Answer

(1) They take up space.. Both air (a gas) and a pencil (a solid) are forms of matter. All matter, by definition, occupies space. A pencil has a fixed shape and volume, while air does not; air can also be compressed, but a pencil cannot.

Question 7

The set-up below shows light shining on a tennis ball. Which one of the following would likely be seen on the screen?

Accepted Answer

(4). A tennis ball is an opaque, spherical object. When light shines on it, it blocks the light and casts a shadow. The shadow of a sphere on a flat screen will be circular and solid (dark). Option (4) shows a solid circular shadow.

Question 8

Which one of the following is NOT a source of heat?

Accepted Answer

(4) A woollen sweater. The Sun, a lighted bulb, and a candle flame all generate and emit heat. A woollen sweater acts as an insulator, reducing heat loss from a body, but it does not produce heat itself.

Question 9

Study the table below. Which one of the following is a mushroom?

Accepted Answer

(2) X. Mushrooms are fungi. They reproduce by spores and cannot make their own food. They are typically visible to the naked eye. From the table: X reproduces by spores and does not make its own food. W makes its own food (plant). Z can only be seen under a microscope (microorganism). Y reproduces by spores but its food-making ability is not specified. Assuming X best fits the definition of a mushroom among the choices.

Question 10

Sarah wanted to find out if the number of leaves would affect the height of a plant. She used two similar pots of plant for her experiment. The table below shows the details of her experiment. Which of the following was the reason why her experiment was not a fair one?

Accepted Answer

(1) The amount of water given daily was different.. For a fair test, only the independent variable (number of leaves in this case) should be changed, while all other variables should be kept constant. The table shows that the amount of water given daily was different (160 cm³ for Pot X and 190 cm³ for Pot Y), which is an uncontrolled variable, making the experiment unfair.

Question 11

The bar graph below shows the amount of digested and undigested food just before it leaves each organ of the digestive system. Which one of the following letters represents the mouth?

Accepted Answer

(3) C. In the mouth, mechanical digestion (chewing) and the beginning of chemical digestion (starch breakdown by salivary amylase) occur. Therefore, some food should be digested before leaving the mouth. The 'Gullet' shows no digestion. Among A, B, C, D, option C shows a significant portion of food already digested, indicating it is an active site of initial digestion, making it the most suitable representation for the mouth among the choices for the start of the digestive process where digestion happens.

Question 12

The graph below shows the number of days for each stage of the life cycle of insect A. Based on the graph, which of the following statements is true about insect A?

Accepted Answer

(2) It hatches from the egg after the 15th day.. The graph shows the egg stage lasting 12 days. Thus, hatching would occur on the 13th day (after 12 days have passed). Statement (2) suggests hatching 'after the 15th day'. While this directly contradicts the 12-day duration shown in the graph, given that the other options (1, 3, 4) are clearly false based on direct interpretation of the graph data, this option is presented as the intended correct answer. This could imply an unstated external factor influencing hatching time or an error in the question/key.

Question 13

Four metal bars W, X, Y and Z were hung from a rod. The metal bars moved in different directions as shown. If only two of the metal bars are magnets, which metal bars, W, X, Y or Z are most likely to be magnets?

Accepted Answer

(1) W and X. Repulsion is the only definitive test for magnetism. If two objects repel each other, both must be magnets. The diagram shows that bar W repels bar X. Therefore, both W and X must be magnets. Since the problem states that only two metal bars are magnets, W and X are the two magnets.

Question 14

Study the flow chart below. What could A, B and C be?

Accepted Answer

(2) air, water, pencil. A substance that does not have a definite volume is a gas (A = air). A substance that has a definite volume but not a definite shape is a liquid (B = water). A substance that has both a definite volume and a definite shape is a solid (C = pencil).

Question 15

Adam set up an experiment as shown below. Then he added solids X and Y to Set-up A and Set-up B. Based on Adam's observation in the set-ups above, what conclusion could he make about solids X and Y? A: Solid X has a greater mass than solid Y. B: Solid Y occupied more space than solid X. C: The amount of space a matter occupied depends on its mass.

Accepted Answer

(3) A and B only. From the weighing scale (Set-up A), Solid X causes the pan to go down further than Solid Y, indicating Solid X has a greater mass than Solid Y (Statement A is correct). From the displacement method (Set-up B), the water level rises higher for Solid Y than for Solid X, meaning Solid Y occupied more space (had greater volume) than Solid X (Statement B is correct). Statement C is incorrect because mass and the space occupied (volume) are independent properties; for example, a less dense object can have less mass but occupy more space, or vice-versa, as demonstrated by X having more mass but less volume than Y.

Question 16

An experiment was set up in a dark room using a torch, a cardboard with a cut-out star and 3 different materials A, B and C. The table below shows the property of each material. How should the materials be arranged such that the patch of light was seen clearly at Position 2?

Accepted Answer

(4) C A B. Material A does not allow light to pass (opaque), B allows some light (translucent), and C allows all light (transparent). For a patch of light to be seen clearly on the screen after Position 3, light must pass through. If C (transparent) is at Position 1, the star-shaped light passes through. If A (opaque) is at Position 2, it would block all the light, preventing any patch from reaching the screen. However, based on the provided answer key, C, A, B is the correct arrangement. This implies a non-standard interpretation of 'seen clearly at Position 2' or a flaw in the question/options as typically interpreted for light transmission.

Question 17

The diagram below shows the shadow of a stick formed at different times, 8 a.m., 10 a.m., 2 p.m. and 5 p.m. of the day. The Sun appears to be moving in the direction as shown by the arrow below from morning to evening. Which of the following is likely to be the shadow formed at 10 a.m. in the morning?

Accepted Answer

(4) Position S. As the Sun moves from left (morning) to right (evening), the shadow cast by the stick moves from right to left. Shadows are longer when the sun is low (early morning/late evening) and shorter when the sun is higher (mid-morning/mid-afternoon). Position S shows a long shadow pointing right, which is typically seen in early morning (e.g., 8 a.m.) when the sun is low in the east (left). Position R, being shorter and still pointing right, would typically represent mid-morning (e.g., 10 a.m.). However, based on the provided answer key, Position S is indicated as 10 a.m., suggesting a specific interpretation of the shadow progression or an error in the question.

Question 18

Maxi conducted an experiment in a dark room using the set-up below. He saw a shadow of the arrow on the screen. What should he do if he wants to increase the size of the shadow?

Accepted Answer

(2) Move the arrow nearer to the torch.. To increase the size of a shadow, the object casting the shadow must be moved closer to the light source (torch). This causes the light rays to diverge more widely around the object before hitting the screen, resulting in a larger shadow.

Question 19

Sam added ice cubes into his glass of warm water. The ice cubes melted after a while. How does adding ice cubes make the water cooler?

Accepted Answer

(2) The ice cubes gain heat from the water as it melts.. Heat always flows from a warmer object to a cooler object. The warm water is warmer than the ice cubes. Therefore, the ice cubes absorb (gain) heat from the water to melt, causing the water to lose heat and its temperature to decrease, making it cooler.

Question 20

Peter observed that there are gaps between the bricks on a footpath as shown. Which of the following explains the purpose of having these gaps?

Accepted Answer

(1) To allow space for the bricks to expand on a hot day.. Materials expand when heated. On a hot day, the bricks will expand. The gaps (expansion joints) are intentionally left to accommodate this expansion, preventing the bricks from pushing against each other, buckling, or cracking the footpath due to thermal stress.

Question 21

Siti conducted an experiment to find out how different materials affect heat gain. She wrapped 3 identical bottles with 3 different materials A, B and C. She then poured in equal amounts of water at 4°C into each bottle. After 10 minutes, she measured the temperature of the water in each bottle and recorded it in the table below. Which of the following arranges the materials from the most effective at reducing heat gain to the least effective?

Accepted Answer

(1) B, A, C. The experiment measures how well the materials reduce heat gain. The initial water temperature was 4°C. A lower final temperature indicates less heat was gained, meaning the material is a more effective insulator (better at reducing heat gain). Material B resulted in the lowest temperature (7°C), making it the most effective. Material A (12°C) is next, and Material C (18°C) is the least effective. So the order is B, A, C.

Question 22

Alan placed a heat sensor attached to a datalogger in a beaker of cold water. Then, he placed a heat source under the beaker. Which of the following graphs shows the likely change in temperature of water over time?

Accepted Answer

(2). When a heat source is applied to cold water, the water's temperature will increase as it absorbs heat. Once the water reaches its boiling point (100°C for pure water at standard pressure), its temperature will remain constant even as more heat is supplied, because the absorbed heat (latent heat of vaporization) is used to change the state from liquid to gas. Graph (2) correctly depicts this: temperature increases, then plateaus.

P4 Science SA2 2023 — Tao Nan

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